Process for the separation of the constituents of gaseous mixtures by liquefaction



Sept. 20, 1932. A ETlENNE 1,878,123

PROCESS FOR THE SEPARATION OF THE CONSTITUENTS 0F GASEOUS MIXTURES BY LIQUEFACTION Filed Oct. 30, 1926 3 Sheets-Sheet 1 Fig.1.

Sept. 20, 1932. A. ETIENNE E E 1,878,123'

PROCESS FOR THE SEPARATION OF THE CONSTITUENTS' 0F GASEOUS MIXTURES BY LIQUEFACTION Filed Oct. 50, 1926 3 Sheets-Sheet 2 ii I '1 11] l1 Sept. 20, 1932.

A. ETIENNE I PROCESS FOR THE SEPARATION OF THE CONSTITUENTS OF GASEOUS MIXTURES BY LIQUEFACTION Filed 00;. so, 1926 3 Sheets-Sheet 5 W dg red/ ELuan/ne,

Patented Sept. 20, 1932 UNITED stares PA rE-Nr oF IcE AL E ETIENNE, E MoN'rEEEAU, FBANCE, Assr noE TO'LA SOCIETE reA'rE EI UIDE,

SOCIETE ANONYME POUR LETUDE ET CLAUDE, OF PARIS, FRANCE LEXPLOI'FATION nEs P ocEnE's GEORGES PROCESS FOR THE SEPARATION OF THE consrrrunn'rs 0E oA'sEousMrxrUEEs'Bf LIQUEFAGTION Application filed October 30, 1926, Serial No.' 145, 232,' and in France December 24, 1925 T his ii' veution relates to processes for the separation of the constituents of gaseous mixtures by liquefaction and particularly to processes for the extraction of hydrogen by liquefaction of the other gases accompanying it in the gaseous mixtureto'be treated; in

whatfollows. this particular case alone will be considered by way of exampleso as to-facilitate the explanation and description 0t the process. a

As has been described in a number of priorpatcnts as igned to bocite LAirr Liquide and relating to the treatn'ient of hydrogen ctmtaining gases by partial llquef action, the

Compressed hydrogen issues at the end of a system of tubes which are subjected to progressively lower teu'ipcratures and wherein the condensation is effected under conditions of backward return of thclcss volatile products; the. hydrogen issuing from the said system of tubes is delivereddirectly, or after heing reheated to some extent, to an expansion motor in which it is expanded, wherea-fter the cooled expanded gas is recirculated through a compartment in which the end part of the tube system islocated and which is thus cooled to the lowest temperature produced in the liquefaction apparatus. For the difterent cases which occur in practice processes based upon this principle, and the present invention likewlse has for 1ts ob ect improvements in this method of operation.'- According to the present invention, 1n-- stead of expanding the hydrogen either directly "or after reheating it in an apparatus distinct from the separation column, such current and in indirect contact with the gases during the course of theseparation process; In the part of the tube system round which the expandedhydrogen circulates, the calorific capacity of this expanded hydrogen is less than that of the gaseous mixture circulating in its indirectcontact by an amount I corresponding to the quantity of the liquidwhich is formed in this compartment and flows back into the lower compartments, 's'o avoided.

there have been described various modified mediate part that bytl a present method the cooling efl'e'ct of the expanded hydrogen is thus. increased by the effect of the compressed hydrogen; the

this the heating'ofthe compressed hydrogen takes place with a difference of temperature as low as possible between thetwo currents of compressed gases, and at the same time, owing to the reheating of the compressed hydrogen, its expansion with the production: of external work can be effected under betterconditions, and heat losses that otherwise result from the use of an external liquefier are p In orderthat the said invention maybe clearly understood and readily carried into effect, the same will now be more fully-described with reference to the accompanying drawings, which illustrate diagrammatically and by way of example, three forms 'of apparatus for carrying out the present process. In said drawings, Figure 1 represents an apparatus for treatlng coke oven gas, ac-

cording to the invention Fig. 2,an apparatus for treating water gas or like gas and Fig. 3 represents a modification comprislng an auxiliarynitrogen liquefier and a column for;

rectifying thehydroge'n under pressure by the liquid hydrogen.

Referring to the apparatus shown in Figure 1, which is suitable for the treatment of a gaseous mixture such as coke oven gas; M is the lower part of a separating column in whichthe main condensation'that takes "place is that of methane and similarg'ases. The ascending ases then pass into the interof the column and thence to H into the tubeseT of the upper part Not the column in which the condensation of their condensable constituents continues' to' take place; the condensates produced in the tubes T 'are'collected in a receptacle D in a liquid are dischar ed into the receiver A from which ows down round the-tubes-T.

sent back from the top of t liquefier fed by a partof the gases to be or tube U having a controlling va ve V and the liquid ,The condensation-in the tubes T is efi'ected in the lower part of the compartmentN with the aid of the cold of the'external liquid "whichflo'ws from thereceiver A round theexterior of thetubes T, and in the upper part of said compartment N with the aid of the cold of the expandedhydrogen which enters through the inlet R and passes out through the outlet E, whilst in the entire height of compartment N the condensation takes place hydrogen which, after issuing from the to gotthe tubes T into the upper collector G 15 e system of tu es to the bottom in indirect and methodical contact with. the ascending gases by passage through the interior of the tubes t inserted ,in the tubes T. The hydrogen which is thus reheated passes into the receiver F whence it is delivered through the pipe W to the expansion device S, and after expansion therein it is returned to the column through theinlet R to cool the top of the nest of tubesxas previously described. If'desired and in order "to complete the reheating of the hydrogen', should this be necessar there may be inserted in-the, ath of the ydrogen between the receiver, v and the expansion deviceS a treated upon their exit from the temperature exchangers through which the said gases to be treated are passed prior to their entering the separating column proper, the hydrogen on its way to the expansion known in the art one being shown, for example, inPatent ldo. 1,579,348, granted April 6, 1926, to Georges Claude, for which reason illustration'thereof in the present case is deemed unnecessary.

' It is particularly importantthat the hydroupper end other tubes contaminated by the liquids which may be accidentally carried along through the tubes end is immersedin the liquid in the collector D, The tube K is intended to return automatically into the receptacle D any liquid which may be carried up through the tubes Tinto the collector G. An arrangement of this kind can beutilized inall analogous cases with the same object in view as just mentioned. Instead of an hydraulic seal the tube r device and the [gases to be treated passing through the li ueer vin indirect contact-with one anot er.- Liquefiers usedin this connection are well 7 ich-is very poor in carbonmonoxide) that is obtained by this process should notbe. 50,

K may provided at its lower end with an outlet orifice of small diameter whereby the same result is obtained.

. In the apparatus shownin Figure 2 which I is designed for the treatment of water gas or similar gases, the gas to be treated upon its egress from the temperature exchangers is admitted to the bottom of the separation column through the inlet A'- and ascends through the tubes T of the single tube system, progressively losing during its ascent its carbon monoxide and eventually its nitrogen; these gases flow back in the liquid state to the I jlower collector D whence they re-ascend with the aid of the cold of the compressed through the tube U and are discharged into the receiver A from whichthe liquid flows down round the :tubes T. The compressed hydrogen which arrives at the .top of the group of tubes-1T then enters," as in the case which the. com ressed hydrogen passes to the expansion device through the pipe 8 and thence, after its expansion, through the inlet R at the top ,of'the column and round the stem of tubes as described above, finally leavmg the column through the outlet E and then passing to thetemperature exchanger. The reheating of the, hydrogen in this arrangement is more complete than in the apparatus shown in Figure 1 as it is eifected up to the neighborhood of the temperature of admissionof the gases into the separation column and its expansion with external work can be accomplished directly under better conditions-than with the preceding arrangement. As in the apparatus of Figure 1 the tube K, which only projects slightly above the tube plate X of the upper collector G and has its lower end immerced in the liquidqwhich .flows into the collecting receptacle D, serves to returntowards the bottom of the column 1 any liquids which might he accidentally carried along through the tubes T. 7

It will be understood that the reheating of the compressed hydrogen up to the .neighbourhood of the temperature of admission ofthe gases into the separation column may be used in the case of mixtures of gases more complex than water-gas, in which case there are employed several sections of superposed tube systems with several collectors for the various li uids formed. a a

The hydrogen issuing from the expander may be returned directly to the top of the tube system as in the apparatus illustrated in Figure 2, or it can also be usedfor liquefying the auxiliary nitrogen which is then delivered in the liquid state to a special compartment of the separation column located round, the top of the tube system. T where it vaporizes and produces the low temperature required for effecting the final purification of the compressed hydrogen. If the nitrogen liquefied by-the expandedhydrogen is 7 produced under asuflicient pressure, it can even be delivered intp a rectification column so as to subject the-compressed hydrogen which issues from the top of the tubes T to a washing treatment which will result in an effective elimination of the carbon monoxide.

It will be understood of coursethat this latter procedurewill only be applicable in cases where thepresence of a considerable proportion of nitrogen in the hydrogen produced is not a matter of consequence. g a

Figure 3 shows diagrammatically an apparatus for carrying out this last modified process in the case of coke oven gases. These gases arrive at A, ascend a first set of tubes T where they are cooled both by the separated gas circulating downwardly through tubes. t and by the'evaporating liquid discharged at B and derivedfrom the liquid collected at D- and ,passing through pipe U1: provided with valve V This liquid is composed mainly of. methane which issues at K as gas. p

The ascending-gas coming from tubes T then ascends tubes T Where itis cooled both by the separated gas circulating downward ly through tubes t and first by the evaporating liquid "(chiefly carbon monoxide and nitrogen) derived from collector I) through pipe U and valve V then by the expanded separated gas circulating in chamber QE, and

finally by the liquid nitrogen evaporating in chamber Q The separated gas rich in bya'drogen issuing through pipe X circulates then through the rectifying column Y:where it meets liquid nitrogenithe resulting gaseous mixture, very rich in hydrogen and nitrogen, escapes through pipe Z, circulates downwardly through the whole length of tubes t, issues at the bottom through pipe \V, 1

and expands in engine S, the expanded cold gas circulating in liquefier L where it liquefies the nitrogen which arrives in a compressed and cold state at N The expanded gas then passes through pipe R to chamber Q while the liquid nitrogen from the li uefier is delivered to chamber Q and rectihcation column Y through pipes O and P that branch from a vertical pipe N connected to the bottom of said "liquefier.

It may furthermore be mentioned that the gaseous mixtures which are treated for the extraction of the hydrogen therefrom usually contain more or less nitrogen; in consequence of the very low temperature to which the gases treated in accordance with the presciit process are subjected, this nitrogen is liquetied to a very large extent in the neighbour- V hood of the upper parts of the tubes T of the apparatus described and the washing cf-f fected by this liquid nitrogen reinforces the effect of the low temperature in eliminating remedied by, re-heati' the carbon monoxide in a very efiicacious manner. Y

It may happen however that this'elimin'ation of nitrogen from the hydrogen at the top of the tubes T takes place to an extent v to interfere with the working of the expander owing toa, lack of lubrication. This disadvantage can be overcome by efiectin an improvement in the cooling conditions sending to the expander, simultaneously with the reheated compressed" hydrogen, a certain quantity of compressedcnitrogen which has been cooled, in a temperature-exchanger, for example in the cases of the treatment of coke oven gases bymeans preferably of the ethylene and a condense V v v ,This deficiency of nitrogen may also be tunder pressure the liquids rich in nitroge plied by the upper collector, this reheating'being effected in such manner that the nitrogen is made to reenter the gases which ascend in the last sect on of the tube system, with't-h'e result that an increased washing andhence a l nore;com

at the top of the expander. v t 7 It is to be understood that the processof the present invention is applicable to the separation by partial liquefaction of the constituents of gaseous'm'ixtures other than d rogeircontalnmg 'nnxturesl Having nowhparticularly described andgas part of the methane which are first certainedthe'n'ature of'my said invention and I in what Lmannerthe same is to be performed, I declare thatI claim is j I i 1. A methodof separatingthe constituents of gaseous mixtures by cold, which co1nprises subjecting to alpartialliqucfaction the gaseous mixture under pressure; expanding the non-liquefied gaseous part resulting from said partial liquefaction; circulatin the gaseous mixture under pressure which is undergoing. partial -'liquefaction I in indirect contact with the compressed non-liquefied gaseous .part resulting from said partial liquefaction; and circulating the said nonliquefied gaseous part, after expansion, in

indirect contact with the above portion of the gaseous mixture under pressure which' 'is ci'rculating inj indirect contactwith the"compressed non-liquefied gaseous part. i

" "2. A method of separating the constitucuts of gaseous mixtures by cold, whichcomprises subjecting to a partial liquefaction the gaseous mixture under pressure; expanding the non-liquefied gaseous part resulting from. said partial liquefaction; circulating the gaseous mixtureunder pressure which 'is'.

undergoing partial "liquefaction, upwardly and in countercurrent with the compressed,

separated, gaseous, part resulting from said gas and with the compressed, separated'gaseouspart.

\ Amethod of separating'th'e constituents ofgaseousmixtures by cold, which comprises )artiall -li, ue'fvin the aseous mixture un- .l a 2'1 1'1 der pressure; collecting the liquids thus formed; relieving the pressure of said liq v 2o uids, circulating the gaseousmixture under pressure in indirect contactwith the said liquids. and evaporating the latter to bring about: the partial liquefaction of the compressed gaseous mixture; further cooling the gsaid gaseous mixture; expanding the re qmaining gaseous part; and circulating the Q same in indirect contact witlithe gaseous j'm'ixtur'e under pressure, While maintaining said mixture in indirect contact with the said remaining gaseous part before expansion. t v V 5, A1n1ethod of separating the constitucnts of-gaseous mixtures by cold, which com- "prises partially llquefyin'g the gaseous mix- .thus obtained; expanding the compressed, separated, V

a-nd saul compressed gaseous parts simultaneously in the liquefaction of said gaseous.

40 u'iixture; and further cooling the gaseous m xture by simultaneous indirect contact both with the compressed,separated, gaseou'sfmrtand with the said gaseous part expanded.

4b 6. A method of separating theconstituents of gaseous mixtures by cold, which comprises subjecting the gaseous mixtureunder pressure to a partial liquefaction; collecting the liquids resulting from said partial liquefaction; and circulating theseparatcd, compressed, gaseous part resulting from said liquefaction in indirect contact with the interior part of streams of the compressed gaseons mixture, while circulating the external part of said streams in indirect contact with i the priorcollected liquids, the evaporation of which brings about thepartial liquefaction of t-he'c'ompressed gaseous mixture. v 7 A method of separating the constituents of gaseous mixture by cold, which comprises subjecting the gaseous mixture under "pressure to a partial liquefaction; circulating'the separated, compressed, gaseous part resulting V from said partial liquefaction in indirect contactwith the interior part of streams of-the simul- 'taneous indirect contact lJOtlLWItll expandedture under prcssure; c ollecting the liquids gaseous part; using said liquids compressed, gaseous mixture, while circulatlng the external part of said streams in 1ndirect contact with evaporating liquids; ex-

panding said separated gaseous part; and then using it for the cooling of the gaseous mixture. l

8. A n'lethodof separating the constituents of gaseous mixtures by cold, which comprises subjecting the gascousmixture under pres sure to a partial liquefaction (circulating the separated, compressed, gaseous part resulting from said partial liquefaction in indirect con tact with the interiorp'art of streams of the compressed gaseous mixture, while circulating the external part of said streams in indirect contact with evaporating liquids; expanding said separated, gaseous part; cooling another gas under pressure by said expand cd gaseous part; and then cooling the gaseous mixture uiulergoingpartial liquefaction by the said expanded gaseous part and the liquefied other gas.

' 9. A method of separating the constituents of gaseous mixture by cold, which comprises subjecting the gaseous mixture under pres: sure to a partial liquefaction; circulating the separated, compressed, gaseous part resulting from said partial liquefaction in indirect contact with the interior part of streams of the compressed gaseous mixture, while circulating the external part of said streams in indirect contactwith evaporatingliquids; expanding said separated gaseous part; liquefying' another gas under pressure by indirect contact with said expanded gaseous part;

cooling the compressed gaseous mixture by the said expanded gaseous part and apart of the liquid other'gas; and washing the compressed gaseous part resultingfrom the partial liquefaction by another part of the said liquefied other gas.

In testimony whereof I aflix my signature. ALFRED ETIENNE. 

